1. Field of the Invention
The invention relates to a continuously working press, and, more particularly, to a continuously working press for the production of chipboards, fiberboard, plastic boards, plywood boards or the like.
Such presses typically include flexible, endless steel bands which transmit the pressing force and draw the article to be pressed through the press and which are supported with an adjustable press nip against abutments of a press platen and a press ram via co-rotating rolling rods guided with their axes transverse relative to the running direction of the band. The angle of the entry gap is varied by way of an adjusting device in the press ram.
2. Discussion of the Related Art
A continuously working press of this type is described in German Offenlegungsschrift No. 2,448,794, (see related U.S. Pat. No. 3,981,666) in which, the angle of the entry gap is variable by means of an adjusting device in the press ram. In this adjusting device, an articulated beam in the press ram is displaced by raising or lowering the upper deflecting drum, with the articulated beam rotating about the axis of rotation of an intermediate drum and forming a rigid entry region between the two drums. The rolling rods, being supported on a rigid rolling surface in the entry region, cannot self-stabilize in their longitudinal axis under differing pressure conditions arising from the article to be pressed. This creates a danger that the rolling rods will not arrive in the high-pressure region perfectly at right angles to the feed direction. This in turn means that the rolling rods are no longer an exact distance from one another. A run-on of the rolling rods and their destruction could be the consequence.
Another disadvantage of the previously known press is that the entry region consists of a single rolling surface, and the angle of the entry gap therefore has to be adjusted via an axis of rotation. However, the permissible steel-band bending/buckling load requires at least a radius in the pivot axis which is 500 times larger than the steel-band thickness. But in view of the steel-band bending/buckling load, a setting angle of only approximately 2.5 can be obtained, since the wear of the steel bands at this location would otherwise be too great. However, a larger angle is necessary to produce chipboards with low-compressed covering layers, and is also necessary for the starting operation.